China’s largest city, Shanghai, is now home to the world’s longest metro system. The Shanghai Metro opened parts of Lines 12 and 16 on December 29 — the rest will follow in 2014 — and now measures 567 kilometers, or 352 miles, in length, edging out Seoul for the world’s top spot. Shanghai’s subway network is probably the fastest growing on earth, with a few new lines and extensions opening each year and many more in planning.

Shanghai does not, however, have the most comprehensive urban rapid transit network. That honor belongs to Tokyo, whose railway network makes every other city’s look puny by comparison. While Shanghai has concentrated all of its investment in subways, Tokyo’s network evolved largely through the upgrading of existing railways. Formally, Tokyo has barely more than 300 kilometers of metro lines between its two subway companies. But it also has a sprawling network of private suburban railways that provide service indistinguishable from that of a subway and which carry many times the number of commuters. In many cases, suburban trains become subways as they run straight onto either Tokyo Metro or Toei Subway tracks to reach the city center, further blurring the line between what’s a subway and what’s a commuter railway.

Drama in Panama

The Panama Canal is growing, but not without a fight. In 2009, a consortium led by Spanish construction firm Sacyr won a $3.1 billion contract to build a third set of locks for the transcontinental canal, to allow larger ships to pass through. But now the contractors are engaging in a high-stakes game of chicken with the Panama Canal Authority over a cost overrun of $1.63 billion, a little more than half the value of the contract. Sacyr and its partners said on Thursday that they will abandon the work unless the authority agrees to cover the overrun. The authority responded yesterday: “The notice of intent to suspend work is not valid and the arguments raised by the contractor in the note lack legal basis and are not clear.”

The problems were foreseen years ago when, according to a leaked U.S. State Department memo, Panama’s vice president and foreign minister privately complained the Sacyr-led consortium was “very weak” and that he had “real doubts” about their ability to perform. He said on a different occasion:

You don’t mess around with something as important as the Canal. When one of the bidders makes a bid that is a billion dollars below the next competitor, then something is seriously wrong. Of course I hope for the best, but I’m afraid that [Canal administrator] Alberto [Aleman] has made a big mistake.

Everybody knows the canal expansion will happen — it’s already mostly complete, and many billions of dollars in ship orders are on the line, as are dredging projects in ports across the eastern seaboard to handle a new influx of ships. Who will shoulder the cost, however, remains to be seen. Spain’s Minister of Public Works, Ana Pastor, flew to Panama and has meetings on Monday with the country’s president and others to try to find a solution.

Maglev Construction Starts in the Fall

The world’s most audacious railway project is about to begin. The Central Japan Railway Company, or JR Central, is set to start construction on its maglev project in the fall, according to Kyodo News. The Chūō Shinkansen, as the line is called, will eventually relieve the Tokaido Shinkansen, the world’s busiest high-speed rail line between Tokyo and Osaka. The first segment of the 505 km/h (311 mph) line will extend from Tokyo to Nagoya, reducing the 100-minute journey to just 40 minutes. JR Central hopes to have permits in hand by the summer, and may even offer paid test rides to the public.

Due to the loud noise that such a train makes as well as the need for very straight tracks, the maglev line will run underground for most of its length. In Tokyo, it will go as deep as 100 meters, or about 30 stories, below the ground.

Stephen J. Smith is a reporter based in New York. He has written about transportation, infrastructure and real estate for a variety of publications including New York Yimby, where he is currently an editor, Next City, City Lab and the New York Observer.